This invention relates generally to lasers and more particularly relates to a modulator for a chemical laser radiating in the wavelength region between 2 and 5 microns (micrometers).
Chemical and electrically excited lasers utilizing HF, DF and CO as the laserable material are well known. They radiate in the infrared between approximately 2 and approximately 5 microns. It is frequently desired to modulate the output of such a laser which is often a continuous wave (CW) laser. Particularly in cases where a high and rapidly variable modulation rate is desirable, mechanical modulation is either impractical or impossible.
For this reason an electro-optical modulator would be highly desirable. Such electro-optical modulators include the recently developed transparent ferroelectric ceramics. Among these ceramics is the lanthanum modified lead zirconate titanate (PLZT) system. It is sometimes referred to as a quaternary (Pb,La) (Zr,Ti)O.sub.3. Such PLZT ceramics may have the following furmula: EQU Pb.sub.1-x La.sub.x (Zr.sub.y Ti.sub.z).sub.1-x/4 O.sub.3 ( 1)
An alternate formula is as follows: EQU Pb.sub.1-3x/2 La.sub.x (Zr.sub.y Ti.sub.z)O.sub.3 ( 2)
however, such PLZT polycrystals do not normally withstand the high radiation present in the cavity of a chemical laser. Such radiation might, among other things, heat up the crystal, shatter it or otherwise render it inoperative.
It is therefore an object of the present invention to provide an electro-optical modulator for a high power laser radiating in the wavelength region between approximately 2 and approximately 5 microns.
Another object of the present invention is to cool such a polycrystal so as to prevent it from heating up.
A further object of the present invention is to mount the crystal in such a way that the acoustic impedance of the holder substanitially matches that of the crystal so that mechanical stress waves set up in the crystal are critically damped, that is that they are substantiallly prevented from reflecting back into the crystal.